Rebarring Design Concepts B&S Nov 2011 www.hilti.com
Hilti welcomes you to the world of innovative
products and quality services
Rebarring Design Concepts B&S Nov 2011 www.hilti.com
Agenda
Hilti Introduction
Post Installation of Rebar - Basics
Post Installation of Rebar - Design Concepts and Calculations
Post Installation of Rebar - Application
Open Session - Queries & Feedback
Rebarring Design Concepts B&S Nov 2011 www.hilti.com
At a glance •Hilti is one of the
World's leading
companies specialized in
the field of fastening and
demolition systems in
the construction industry
• Quality
• Innovation
• Extensive application know-how resulting from close contact with customers
Rebarring Design Concepts B&S Nov 2011 www.hilti.com
Principality of Liechtenstein
• Liechtenstein 35’000 citizens 162 square kilometres
Hilti Group More than 19000 employees worldwide About 1’600 in Liechtenstein
Rebarring Design Concepts B&S Nov 2011 www.hilti.com
Production Network
West Bromwich plant
(Great Britain)
Kecskemét plant
(Hungaria)
Strass plant
(Germany)
Tulsa plant (USA)
Thueringen plant
(Austria)
Schaan plant
(Princ. of Liechtenstein)
Mexico City plant
(Mexico)
Mauren plant
(Princ. of Liechtenstein)
Kaufering plant
(Germany)
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TS
FE/MSM
HSC
RM
KOLKATA
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Visakhapatnam
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PUNE
AHMEDABAD
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CHANDIGARH
Baroda
Surat
MSM
KAE
Trivendrum
Guwahati
Koch i
Jamnagar
Gandhidam
Jaipur
Mandi
Ludhiana
SECUNDERABAD
Kurukshetra
Indore
Nasik
Gurgaon
MUMBAI
Goa
BANGALOR
E
BANGALOR
E
MSM
Dehradun
Ranchi
Raipur
Trichy
MSM
M-P
M-P
PRESENCE OF
HILTI
IN INDIA - 2010
Siliguri
M-P
M-P
M-P M-P
M-P
Rourkela
Jabalpur
Srinagar
Mangalore
Hubli
Kolhapur
KAE
Rebarring Design Concepts B&S Nov 2011 www.hilti.com
A complete coordinated offering from Hilti
Rebarring Design Concepts B&S Nov 2011 www.hilti.com
Post-Installed
Rebarring
Technology
Rebarring Design Concepts B&S Nov 2011 www.hilti.com
Rebar Grouting
What Is Rebarring
Adding reinforcement to an existing
concrete structure such that the
structure behaves as a cast in structure
How Is Rebarring Done
• Drill Hole in Concrete based on
design
• Fill it with chemical
• Insert rebar and allow for chemical
curing
Rebarring Design Concepts B&S Nov 2011 www.hilti.com
C) Moment Connections
•Column from Raft/ Pile cap
•Cantilever beam from column
•Bracket on column
B) Spliced Connections
•Extension of column
•Extension of beam/ slab
•Casting slab in a cutout
Applications
A) Simply Supported Connections
•Adding beam between columns
•Casting slab in a cutout
D) Shear Connectors
•Thickening of slabs/ raft
•J bolting while jacketing
Rebarring Design Concepts B&S Nov 2011 www.hilti.com
Misplaced or missing rebars
Post-installation is necessary when there
is a rebar misplaced or completely
missing due to error in construction
Additional rebars
Corrections or additions to be made
due to architectural changes or for
additional strength
Need for post-installation of rebars
Rebarring Design Concepts B&S Nov 2011 www.hilti.com
Extention of slabs, balconies & stairs
Connections of new slabs
Close openings / slab enlargement
Balcony extension
Connection of staircase
Rebarring Design Concepts B&S Nov 2011 www.hilti.com
Extention of columns, beams & walls
Connection of new columns
Connection of beams
Extension of reservoirs
Wall extensions
Rebarring Design Concepts B&S Nov 2011 www.hilti.com
Rebar Grouting
Outcome
• No damage to existing concrete (Cost saving on prepare & repair)
• Precise controlled application (Quality of work & Speed)
• Flexibility in designs
Role of Designer
• To Provide Safe Design
• Right Embedment depth
• Right Steel details
• Right chemical
Rebarring Design Concepts B&S Nov 2011 www.hilti.com
What is Different Now ?
Flow of forces in existing concrete?
Modes of failure?
Is it in alignment with the existing code?
What is different from existing codes?
Rebarring Design Concepts B&S Nov 2011 www.hilti.com
Simply Supported Connections
Challenge: For what force is embedment to be calculated ?
{Cl 5.6.4, EC2:EN 1992-1-1:2004}
{Cl 6.5.1 (1), EC2:EN 1992-1-1:2004}
Rebarring Design Concepts B&S Nov 2011 www.hilti.com
Simple Supported Joints
T = (V cotθ)/2
T = total tension developed = V/2 X cot(θ)
V = applied shear load
θ = Angle between Tension Cord of steel & Compression Strut
(45° > θ > 21.8° as per Euro code 6.2.3)
T
C
V
T
C V
θ1
T = 1.11 V
V
Rebarring Design Concepts B&S Nov 2011 www.hilti.com
Load on Rebar <= Resistance Offered by Rebar
Failures to be Checked
•Bond
•Splitting
•Steel
Calculation of Embedment Depth
EC2 or IS 456
When C/d <=3
When C/d >3
Rebarring Design Concepts B&S Nov 2011 www.hilti.com
Splitting
Rebarring Design Concepts B&S Nov 2011 www.hilti.com
Failure mode of rebars depends on concrete cover
Rebar close to
the edge
Rebar away
from the edge
Rebarring Design Concepts B&S Nov 2011 www.hilti.com
Eurocode 2: a2=1-0.15∙(cd/f-1)
bond strength depending on cover: fbd,cover = fbd/a2
s cx
cy
EC2 limited by
a2,min = 0.7
Splitting design: extension
for post-installed bars with
large cover Inclination derived from tests
Splitting design limited
by bond strength of
adhesive
HIT-Rebar design method (Splitting design)
considers the real adhesive bond strength
1 2 3 4 5 6 2
2.5
3
4.5
6
7
8
9
10
(Confinement or concrete cover)
f bd [
N/m
m2]
cd /Φ
This makes ductile design possible for moment resisting connections with straight bars
IS-456
Rebarring Design Concepts B&S Nov 2011 www.hilti.com
0
2
4
6
8
10
12
14
16
18
20
2 3 4 5 6 7 8 9 10 11 12
concrete cover dimension cd/f [-]
bo
nd
[N
/mm
2] Tests Hilti HIT RE 500
Tests Hiliti HIT HY 150
Tests cast-in
design value EC 2
design value extended EC 2
characteristic ext EC 2
Validation on basis of consolidated tests
0
2
4
6
8
10
12
14
16
18
20
2 3 4 5 6 7 8 9 10 11 12
concrete cover dimension cd/f [-]
bo
nd
[N
/mm
2] Tests Hilti HIT RE 500
Tests Hiliti HIT HY 150
Tests cast-in
design value EC 2
design value extended EC 2
characteristic ext EC 2
0
2
4
6
8
10
12
14
16
18
20
2 3 4 5 6 7 8 9 10 11 12
concrete cover dimension cd/f [-]
bo
nd
[N
/mm
2] Tests Hilti HIT RE 500
Tests Hiliti HIT HY 150
Tests cast-in
design value EC 2
design value extended EC 2
characteristic ext EC 2
Several pull-out tests have been conducted to check consistency in performance
Rebarring Design Concepts B&S Nov 2011 www.hilti.com
Moment Connections
Rebarring Design Concepts B&S Nov 2011 www.hilti.com
Rebarring Design Concepts B&S Nov 2011 www.hilti.com
Frame Node
M 1
V 1
N 1 M1
V1
N1
C
M1
V1
N1
M1
V1
N1
C
Rebarring Design Concepts B&S Nov 2011 www.hilti.com
M 1
V 1
N 1
z1R
d
ℓb
linst Zo
θ
T1 = M1/z1R +N1/2 +V/2 Cot (θ)
Z1R = 0.9*d
30o<θ<60o
Finding Safe Embedment
• Find Basic Anchorage Length (lb) due
to Splitting/ Bond for Force T1
• Calculate Linst = cu + Z1r tan(θ) + lb/2
Rebarring Design Concepts B&S Nov 2011 www.hilti.com
Additional Checks
1. Concrete Capacity against Compressive Strut
2. Capacity of perpendicular rebars against additional forces
3. Tensile Capacity of Concrete Against Splitting Forces
Rebarring Design Concepts B&S Nov 2011 www.hilti.com
T1 = M1/Z +N1/2 +V/2 Cot (θ)
Splice Connections
• Load Transfer Mechanism: 45o Compressive Struts
• Ideal Clear Spacing between bars < 4XΦ
Calculation Steps
1. Calculate Load T1
2. Find Embedment Required for Post-Installed Rebar
• Use Hilti Method to Check for Bond/ Splitting
3. Find Embedment Required for Cast-In Rebar
• Use Regular Country Codes (EC2, IS 456)
4. Required Splice Length = Max (Post Installed; Cast-In)
5. Multiply with Additional Factor α6 = 1.5
Rebarring Design Concepts B&S Nov 2011 www.hilti.com
HIT-Rebar design method overcomes code limitations and
hence provides post-installed solutions otherwise not
feasible
Summary
Use HIT-Rebar design method to utilize the full bond
strength of the Hilti adhesive by going beyond Eurocode
2
1
2
Rebarring Design Concepts B&S Nov 2011 www.hilti.com
Beyond Design…
Chemical Selection may depend on parameters like:
• Temperature range (long/ short)
• Drilling method
• Effect of chemicals
• Creep Behaviour etc…
Special Care in Application with Deep Embedment
• Proper Cleaning
• Usage of Piston Plug
• Application Video..\..\Rebarring\Rebar campaign\Profi
kit video\HILTI-REBAR-MOVIE-V2.0EN.mpg
Rebarring Design Concepts B&S Nov 2011 www.hilti.com
Hilti Support to Designers
• Provide Calculation Reports as per EC2/ EOTA TR 023/
Hilti Rebar Method
• Provide tools for calculation – Software Profis Rebar,
Manuals etc.
• Provide Technical Approvals/ Certificates
• Testing at Site
• Training on Software
Rebarring Design Concepts B&S Nov 2011 www.hilti.com
Hilti Services
Design (Free of Charge)
• Selection of Chemicals
• Design based on international codes
• Specifications
• Rebar Pull-out Testing at site
Application
• Training at site( Free of Charge)
• Trained applicator Network
• Repair facilities for all tools used in
rebar grouting applications
Rebarring Design Concepts B&S Nov 2011 www.hilti.com
Thank You
Ashish Mittal (9811150266)